Well formation isolation apparatus



March 16, 1965 s. c. BRETZKE, JR

WELL FORMATION ISOLATION APPARATUS 2 Sheets-Sheet 1 Filed Aug. 26, 1958Filer Cake FIG. I.

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March 1'6, 1965 s. c. BRETZKE, JR

WELL FORMATION ISQLATION APPARATUS 2 Sheets-Sheet 2 Filed Aug. 26, 1958r., s. 4 .d m y e s m 9 m m 2. MU @d m u TT w M A H 2 1.. :rn i v 4 .0 M.k m m -`l=n u 7\\\\ m Ww SY m B C 6 G. M M 3 n H 4. G. w F s. u H

Filter Coke United States Patent Cil ce 3,173,485 Patented Mar. 16, 19653,173,485 WELL FRMATION ISOLATION APPARATUS Samuel C. Bretzke, Jr.,Houston, Text, assigner to Halliburton Company,a corporation of DelawareFiled Aug. 26, 1958, Ser. No. 757,266 6 Claims. (Cl. 16o- 100) Thisinvention generally relates to the testing of earth formations traversedby a well bore and more particularly relates to new and improvedapparatus for conducting such testing operations from a hoisting cable.

This invention is particularly suitable for use with apparatus such asdisclosed in copending and commonly assigned application to Durward B.McMahan, entitled Well Formation Testing Apparatus, Serial No. 712,190,filed January 30, 1958.

As mentioned in the above copending application, there is an existingneed for well formation testing apparatus which may be rapidly andeasily lowered into the well bore from a hoisting line and obtainaccurate data from well formations which may contain oil and gas incommercial quantities. A pertinent problem in existing wire line toolsis that of effecting a good seal between such apparatus and the wall ofthe well. Failure of the seal results in valueless samples and pressurerecords of only the drilling fluids.

The hydrostatic uid pressure existing as a result of the weighteddrilling fluids in rotary drilled Well bores may be in the order ofseveral thousand p.s.i. The tluid pressure within a particular earthformation traversed by the well bore is always less than thishydrostatic pressure. A sealing member such as herein disclosed isrequired to effect a seal between the formation and the well bore iiuidsto permit fluid entry from the formation to within the testingapparatus. The chambers of such testing apparatus are initially atatmospheric pressure. As the testing apparatus is opened the pressuredifference between the well bore and the sample charnber will be exertedacross the sealing member as a pressure differential. As fluid lowcommences from the formation into the testing apparatus the pressuredifferential across the sealing member becomes the difference in wellbore pressure and formation pressure. Such differential pressures inmany cases are so great that the sealing member is punctured, allowingfluids to flow directly from the well bore into the testing apparatus.At other times a small initial leakage may exist between the sealingmember and the well bore wall which, at the differential pressuresexisting, will erode channels between the sealing member and formationwall, destroying the value of the test.

It is accordingly the general object of the present invention to provideimproved apparatus which, when forced into contact against the wall of awell formation by testing apparatus as described, will effectively seala portion of such formation from the drilling uids to provide trueformation pressures and pure formation uid samples.

This and other objects of the invention are attained by wire linetesting apparatus having a well formation tluid isolation member in uidcommunication and reciprocative connection with a tester body to beselectively extended into physical contact with the Wall of a wellformation. The isolation member comprises a support member containing afluid chamber in fluid connection with a sample chamber defined withinsaid testing apparatus and in connection with a rear face of a resilientpad member. The pad member is provided of resilient material which isprovided of predetermined selected resistance to deformation. The frontface of the pad member is formed generally complementary to a segment ofthe well bore wall. A rigid conduit is connected into Huid communicationwith the support chamber and extends from the support through the` padmember to the front face. A resilient enclosure member of greaterresistance to deformation than the pad member is disposed around aselected length of the conduit and in bonded connection with the padmember, forming a portion of said pad face. A screening chamber ofsmaller volume than the support chamber is disposed within the supportchamber and connected in fluid communication with the conduit.

Other objects and advantages of the invention will become more apparentfrom reference to the following escription taken in conjunction with theaccompanying drawings, in which:

FIGURE 1 is an elevational View of the complete testing apparatussuspended in a well bore.

FIGURE 2A is a partial transverse cross section taken at 2-2 of FIGURE1.

FIGURE 2B is the section of FIGURE 2A taken at a later stage inoperation of the device.

FIGURE 2C is the section of FIGURE 2A taken at a further stage inoperation of the apparatus.

FIGURE 3A is a longitudinal cross section taken at 3 3 of FIGURE 2A.

FIGURE 3B is the section of FIGURE 3A taken at a later stage inoperation of the device.

FIGURE 3C is the section of FIGURE 3A taken at a further stage inoperation of the device, and

FIGURE 4 is a front elevation of the formation fluid isolation membershown in FIGURES 1 to 3.

Referring to FIGURE 1, a tester tool 10 is shown suspended in a wellbore 12 from a hoisting cable 14. Cable 14 is connected into a hoistingunit (not shown) which is adapted to raise or lower tool 10 to anydesired position within a well bore 12. In electrical connection withtool 1t) through cable 14 is a surface operated electrical control andindicating or recording means (not shown).

Tool 10 generally includes three sections, an upper switch housing 16, atesting body 18, and a lower fluid chamber 2t). A spontaneous potentiallogging electrode 22 is mounted on switch housing 16. Shown at 24 areresilient centralizer arms radially mounted with the body 18 whichcontact the walls of well bore 12 and tend to keep the tester tool 10concentrically disposed Within the bore. Body 1S includes theresiliently faced formation isolation member 26 of the present inventionand a wicker retaining member 28 jointlymountedl in` reciprocalconnection with body 18. Members 26 and 28 may be connected to body 18at their upper end by means of longitudinally diverging dove-tailtrackways and at their lower ends by means of pins extending intolongitudinally diverging slot ways. As illustrated, a transfer rod andcrosshead assembly is provided, said transfer rod having spring loadedpawl arms 30 and 32 mounted thereon in such manner that release of thepawls into contact with the well bore wall and subsequent downwardmovement of body 18 relative to the transfer assembly will transverselyextend members 26 and 28 out from the testing body 1S into contact Withthe well bore wall.-

Pawl arms 30 and 32 and the transfer assembly are provided withelectrical Vmeans of selective release. Also provided in the housing 16are electrical switching means to respectively connect the loggingelectrode 22 and various valving means disposed in body 18 to theco-nductor 14. While FIGURE 1 discloses sufficient detail of such atester 10 to clearly point out the operation of the present invention asdescribedwith respect to FIG- URES 2A and 3A, a more detaileddescription of the .3 complete construction and Voperation of a tester10 with which the present invention has been used may be obtained byreference to the previously mentioned copending application.

Transverse and longitudinal sections of isolation member V26 arerespectively illustrated in FIGURES 2A and 3A. Isolation member 26 isprovided with a support `member 34 which includes a removable coverplate 36. 4Defined within support member 34 is a iiuid chamber 38.Chamber 3S has means of fluid communication into `testing body 18through a fiuid passageway 40. A seal is provided between cover plate 36and support member 34 by means of an O-ring42 or the equivalent.Connected in bonded relation to the front of cover plate 36 is aresilient sealing cushion or vpad 44. Though other bonding 'means arepossible, pad 44 as herein illustrated is bonded lat its back to plate36-by vulcanizing.

Connected-through plate 36 into chamber 3% is a fluid sampler barrel orconduit 46. Barrel rigidly extends through an accommodating hole in pad44 to near the face of the pad. Enclosing the extended portion of barrel46 and bonded to pad 44 is a sealing enclosure member 48, hereinillustrated as being of generally conical configuration diverging towardthe face of the pad.

Pad 44 and enclosure member 48 are both provided of resilient andelastic material such as natural or synthetic rubber. For reasons laterdescribed, enclosure member 48 is provided of material substantiallymore resistant to deformation than pad member 44. As an example, padmember 44 may be provided of durometer ranging about 35 to 45 andenclosure member 48 may be provided of durometer ranging about 60 to 80The term resilient as -used in the appended claims will therefore denotethe properties, including resistance to deformation, exhibited bynatural or synthetic rubbers.

It is noticed in FIGURE 3A that cover plate 36 is undercut at 5t) aboveand below barrel 46 to provide clearance between the plate and pad.Though not absolutely esesntiaL this clearance is beneficial inproviding increased resilience to the pad about barrel 46 and alsoproviding pressure access to the rear of the pad, as later described.

Connected to the sides of support member 34 and disposed in backingrelation to the rear face of pad member 44 are backing members 58. Thesebacking members are usually used only when conducting tests in wellbores of large diameter and may be deleted without injurious effect insmall bores, for example, of less than 8 inches diameter.

Isolation member 26 is connected into testing body 18 by means of anupper guide 52 and a lower guide 54, shown in FIGURE 3A. As shown, theupper guide 52 is mortised for connection to a complementary dove-tailtrackway in testing body 18. Reciprocal connection of member 26 to thetransfer member previously mentioned is made with the lug shown at thelower end of guide 54 in FIGURE 3B.

It is seen, from the sections shown in FIGURE 2A, and FIGURE 3A, thatthe face of pad 44 is of generally arcuate configuration from alongitudinal view and that the face of pad 44 is of radius somewhatsmaller than the anticipated radius of the well bore. Also, as shown inFIGURE 3A, the face of the pad is beveled slightly from its center sothat initial contact of the pad with the well bore will be made in theimmediate vicinity of conduit 46.

Defining four sides of a chamber of smaller dimension within chamber 38is a screen member 56. Screen 56 is connected with barrel 46 in a mannerinsuring that all fiuids entering through the barrel must pass throughthe screen before entering the passageway 49. As shown in FIGURE 2A, theside walls of chamber 3S form the remaining two walls of the chamberdefined by screen 56. This arrangement has been found highly beneficialin that, by removal of the cover plate 36, the screen S6 may bewithdrawn from chamber 3S and the sand, cuttings or other detrituscontained within the screen then removed by merely by allowing suchcuttings to fall out the open sides.

In operation, the tester tool 10 is lowered into the well more to anapproximate depth indicated by previous electrical logs. The loggingelectrode 22 is switched into circuit to give surface indication of thespontaneous potential of the adjacent formation. The testing apparatusis then adjusted, by reference to the indication from electrode 22, tothe exact depth of the promising formation.

The meanns for releasing pawl arms 30 and 32 is then switched intocircuit and actuated, releasing the arms. The pawl arms, in response totheir Spring loading, are then urged into contact in the walls of thewell bore, preventing downward movement of the transfer assembly.

The tester tool l() is then lowered by cable 14, causing relativelongitudinal movement between the tester body and transfer assembly. Theisolation member 26 is urged up the dove-tail having connection withupper guide 52 into contact with the well bore walls.

Such initial contact is illustrated in FIGURES 2A and 3A. It is seenthat the drilling mud filter cake may be partially extruded by thisinitial contact, permitting the inlet of barrel 46 and the face ofmembers 44 and 4S to be in close relation to the bore wall.

The tensions of cable 14 is then released, permitting the entire weightof tester tool 10 to bear, through the illustrated trackways, uponisolation member 26 and wicker member 28. In the embodiment presentlyillustrated, tool I@ weighs about 385 pounds may be additionallyballasted as required, for example, to 600 pounds or more. It is thusseen that the isolation member is extended into very close and forcefulcontact with the well bore wall. Such engagement by the full weight oftesting tool 1) is illustrated in FIGURES 2B and 3B. It is noticed thatenclosure member 48 and a portion of pad 44 have been deformed intointimate contact with the well bore wall. Also, additional drilling mudfilter cake may have been extruded from between the pad and the wall.However, a small amount of filter cake may be expected to remain whichserves an advantage in filling minute declivities of the well bore wall,which may be somewhat rugose, and in generally serving as a gasketingmaterial between member 26 and the bore wall.

Due to the previously described configuration of the face of member 44,the greatest compression and deformation occurs at the enclosure member48 and a portion of pad 44 immediately surrounding the enclosure member.It can be seen that the greatest sealing effect occurs in the vicinityimmediately about the intake of barrel 46. Depending on the hardness ofthe formation, the elasticity of the pad member and the Weight of tool10, the barrel 46 may extend slightly into the formation at this -stageand can be expected to be in contact with the formation.

When provided, the backing members 53 also serve to engage the pad intocontact with the well bore wall at this stage of operation. However, aspreviously described, this baclting feature is not needed for smallerbore sizes and may be deleted in such case.

Since the hydrostatic pressure of the drilling mud or fluids in the wellbore is always in excess of the formation fluid pressures, there willalways be a pressure differential, often of large magnitude, existingbetween the well bore and the formation. Thus, when a portion of theformation is isolated by member 26 and fiuid pressure at the entry ofbarrel 46 is reduced, as by opening a valve to the sample chamber withintester tool 10, this differential pressure is brought to bear across thepad and forces a far more forceful engagement with the well bore wall.

As illustrated in FIGURES 2C and 3C, when fluid communication isprovided through barrel 46 into sample chamber 20, the pressureimmediately about the intake of barrel 46 initially drops tosubstantially atmospheric pressure and permits luid flow from theformation through the barrel 46, screen 56 and passageway 40 into samplechamber 20. The well bore fluid pressure is exerted as a differentialpressure across the pad 44 and enclosure member 48. As shown, the padmember is pressed against the well bore wall in response to suchdifferential pressure, further deforming the members 44 and 48 andcausing the seal established around barrel 46 to become more positive,particularly at enclosure member 48 and at the pad 44 in the vicinityimmediately surrounding member 48.

At this stage of operation the force exerted across the pad member is ofsuflicient magnitude to cause considerable extension of barrel 46 intothe formation. This has been found to be the case even though theformation is hard, impermeable and non-productive.

When in operation adjacent a productive formation the pressure about theintake of barrel 46 rises, as lluid flow begins through the barrel, fromthe initial atmospheric pressure to the native formation pressure. Thepreviously mentioned differential between the hydrostatic pressure ofthe well bore fluids and the formation pressure maintain the forcefulsealing contact illustrated in FIGURES 2C and 3C.

Enclosure member 48 is provided of material having greater resistance todeformation than does the material of member 44 for two major reasons.One of these reasons, as previously mentioned, is that a superior sealis effected immediately about the intake of barrel 46 upon applicationof force from the rear of the member 26. A second important reason forprovision of these materials as described is to prevent rupture throughthe pad member in the vicinity of enclosure member 43. In trial testsmade during the development of this in vention it was repeatedly foundthat the structure as disclosed effectively prevented ruptures throughthe pad formerly caused by the great pressure differential existingbetween the well bore fluids and the formation.

Though disclosed and illustrated as being generally conical in shape andenclosing very nearly the entire extended portion of barrel 46,enclosure member 43 may be and has been successfully provided ofsomewhat different configuration. For example, member 48 may be providedin generally cylindrical form for a distance from the plate 36 and thenextend in conical fashion as disclosed. Also, enclosure member 48 may beof generally cylindrical configuration throughout its entire length.After many experimental field trials it is believed that the disclosedconfiguration is superior.

After the complete sampling operation has been performed, the testertool lil may be withdrawn by taking tension on cable 14. The weight oftester is removed from the extended members 26 and 28. As tester tool 10is raised, members 26 and 28 become free and converge down the dove-tailconnections into retracted position. The transfer assembly drops withinthe tester body 18, permitting withdrawal of the tool 1@ from the wellbore. As the tool is withdrawn the pawl arms 30 and 32 continue to slideagainst the walls of the well bore 12 but cannot engage when moved in anupward direction.

It is to be understood, while only one embodiment of the invention hasbeen disclosed herein, that various changes may be made withoutdeparting from the spirit of the invention. The invention should not beregarded as limited, therefore, except by the scope of the appendedclaims.

That being claimed is:

l. A well bore lluid isolation member adapted for use with a wirelinetesting apparatus, comprising, a resilient pad member of material havingpredetermined resistance to deformation, said pad member having a frontand a rear face, a central portion and a hole defined through saidcentral portion between said front and rear face, a support member inconnection with a portion of said rear face, said support member beingadapted for connection with testing apparatus, said support memberdefining a fluid chamber adapted for iluid communication with testingapparatus, a `substantial portion of said rear face of said pad memberbeing exposed to pressure of well bore fluids, said front face beingIformed generally arcuate to provide an increasing clearance extendingfrom said central portion between said front face and a well bore wall,a rigid conduit connected to said Support member in fluid communicationwith said fluid chamber and extending from said support member throughsaid hole to near said front face, a resilient enclosure member ofmaterial having greater resistance to deformation that said pad memberdisposed around a selected length of said conduit and forming anintegral portion of said pad member, and a screening chamber of smallervolume than said support chamber disposed within said fluid chamber andin fluid communication with said conduit.

2. A well bore fluid isolation member adapted for use with a wirelinetesting apparatus, comprising, a resilient pad member of material havingpredetermined resistance to deformation, said pad member having a frontand a rear face, a central portion and a hole dened through said centralportion between said front and rear face, a support member in connectionwith a portion of said rear face, said support member being adapted forconnection with testing apparatus, said support member defining a fluidchamber adapted for fluid communication with testing apparatus, asubstantial portion of said rear face of said pad member being exposedto pressure of well bore fluids, said front being formed generallycomplementary to a segment of well bore wall to provide an increasingclearance extending from said central portion between said front faceand a well bore wall, a rigid conduit connected to said support memberin fluid communication with said fluid chamber and extending from saidsupport member through said hole to near said front face, a resilientenclosure member of material having greater resistance to deformationthan said pad member disposed around a selected length of said conduitand forming an integral portion of said front face of said pad mem-ber.

3. A well bore fluid isolation member .adapted for use with a wirelinetesting apparatus, comprising, a resilient pad member of material havinga predetermined resistance to deformation, said pad member having afront and a rear face, a central portion and a hole defined through saidcentral portieri between said front and rear face, a support member inconnection with a portion of said rear face, said support member beingadapted for connection with testing apparatus, la substantial portion ofsaid rear face of said pad member being exposed to pressure of well borefluids, said front face being formed generally complementary to asegment of a well bore wall to provide an increasing clearanceexten-ding from central portion between said front face and a well borewall, a rigid conduit connected into said support member and extendingfrom said support member in movable relation through said hole to nearsaid front face, a resilient enclosure member of material having greaterresistance to deformation than said pad member disposed around aselected length yof said conduit and forming an integral part of saidcentral portion.

4. A well bore fluid isolation member adapted for use with a wirelinetesting apparatus, comprising, a resilient pad member of material havingpredetermined resistance to deformation, said pad member having a frontand a rear face, a central portion and a hole defined through saidcentral portion between said front and rear face, a support member inconnection with a portion of said rear face, said support member beingadapted for connection with testing apparatus, said support memberdefining a fluid chamber adapted for fluid communications with testingapparatus, a substantial portion of, said rear face of said pad memberbeing exposed to pressure of well bore tluids, said front face beingformed generally complementary to a segment of well bore wall to providean increasing clearance extending from central portion between saidfront face and a well bore wall, a rigid conduit connected to saidsupport member in fluid communication with said fluid chamber andextending from said support member in movable .relation through saidhole to near said front face, a resilient enclosure member of materialhaving greater resistance to deformation than said pad member disposedaround a selected length of said conduit and forming an integral portionof said pad member, said enclosure member converging along the length ofsaid hole `from said front face in generally conical shape, and ascreening chamber of smaller volume than said support chamber disposedwithin said fluid chamber and in fluid communication with said conduit.

5. A well bore iluid isolation member adapted for use with a wirelinetesting apparatus, comprising, a resilient pad member of material havingpredetermined resistance to deformation, said pad member having a frontand a rear face, a central portion and a hole define through saidcentral portion between said front and rear face, a support member inconnection with a portion of said rear face, said support member beingadapted for connection with testing apparatus, a substantial portion ofsaid rear face of said pad member being exposed to pressure of Well borciiuids, a rigid conduit connected into said support member and extendingfrom said support member through said hole to near said front face, aresilient enclosure member of material having greater resistance todeformation than said pad member disposed around a selected length ofsaid conduit and forming an integral portion of said central portion.

6. A well bore fluid isolation member adapted for use with a wirelinetesting apparatus, comprising, a resilient pad member of material havingpredetermined resistance to deformation, said pad member having a frontand a rear face, a central portion and a hole defined through saidcentral portion between said front and rear face, a support member inconnection with a portion of said rear face, said support member beingadapted for connection with testing apparatus, said support memberdefining a fluid chamber adapted for fluid communication with testingapparatus, a substantial portion of said rear face of said pad memberbeing exposed to pressure of well bore iiuids, a rigid conduit connectedto said support member in fluid communication with said fluid chamberand extendin from said support member through said hole to near saidfront face, a resilient enclosure member of material having greaterresistance to deformation than said pad member disposed around aselected length of said conduit and forming an integral portion of thecentral poriton of said pad member, and a screening Chamber of smallervolume than said support chamber disposed within said uid chamber and insaid uid communication with said conduit.

References Cited in the tile of this patent UNITED STATES PATENTS

2. A WELL BORE FLUID ISOLATION MEMBER ADAPTED FOR USE WITH A WIRELINETESTING APPARATUS, COMPRISING, A RESILIENT PAD MEMBER OF MATERIAL HAVINGPREDETERMINED RESISTANCE TO DEFORMATION, SAID PAD MEMBER HAVING A FRONTAND A REAR REAR FACE, A CENTRAL PORTION AND A HOLE DEFINE THROUGH SAIDCENTRAL PORTION BETWEEN SAID FRONT AND REAR FACE, A SUPPORT MEMBER INCONNECTION WITH A PORTION OF SAID REAR FACE, SAID SUPPORT MEMBER BEINGADAPTED FOR CONNECTION WITH TESTING APPARATUS, A SUBSTANTIAL PORTION OFSAID REAR FACE OF SAID PAD MEMBER BEING EXPOSED TO PRESSURE OF WELL BOREFLUIDS, A RIGID CIRCUIT CONNECTED INTO SAID SUPPORT MEMBER AND EXTENDINGFROM SAID SUPPORT MEMBER THROUGH SAID HOLE TO NEAR SAID FRONT FACE, ARESILIENT ENCLOSURE MEMBER OF MATERIAL HAVING GREATER RESISTANCE TODEFORMATION THAN SAID PAD MEMBER DISPOSED AROUND A SELECTED LENGTH OFSAID CIRCUIT AND FORMING AN INTEGRAL PORTION OF SAID CENTRAL PORTION.